Thanks that is great to know.
I remember my Polar running strap also worked on the Luna but it was not "coded" which I think meant that if two divers were sitting beside each other the wrist unit might pick up the other diver's heart rate or visa versa.
As for cold water and skin temperature we use that old-fashioned sign up here called shivering. The real brain usually sends an alert to shorten the dive and head to the surface.
That being said it would be interesting to know the science behind skin temperature and the DCS algorithm used because it would seem that it is one's core temp not skin temperature which should be integrated into the algorithm.
In order to get at core temperature one would have to use a rectal temperature probe. That could probably be made wireless.